The Yacoraite Formation is a largely

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

geologic

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

. The deposits of this formation mainly date from the

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

of the Upper

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

, but the

Cretaceous–Paleogene boundary The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, is a geological signature, usually a thin band of rock containing much more iridium than other bands. The K–Pg boundary marks the end of ...

(K–T boundary) runs right through this formation near its top, and the uppermost parts are consequently from the

Danian The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian (and the end of the preceding Maastrichtian) is at the Cretaceous� ...

(Lower

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...

). It was probably deposited around the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

, as the

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

s of this formation alternate according to

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...

changes between deposits of muddy beaches and of shallow ocean.Marquillas ''et al.'' (2003)

Fossil content

Dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

remains are among the fossils that have been recovered from the formation.Weishampel ''et al.'' (2004: pp.517-607) Well-preserved dinosaur footprints assigned to '' Hadrosaurichnus australis'' have been found in this formation, as were

fossil egg Egg fossils are the fossilized remains of eggs laid by ancient animals. As evidence of the physiological processes of an animal, egg fossils are considered a type of trace fossil. Under rare circumstances a fossil egg may preserve the remains of t ...

stromatolite Stromatolites () or stromatoliths () are layered sedimentary formations (microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). The ...

s and the Mesozoic

palynomorph Palynology is the "study of dust" (from grc-gre, παλύνω, palynō, "strew, sprinkle" and '' -logy'') or of "particles that are strewn". A classic palynologist analyses particulate samples collected from the air, from water, or from deposit ...

'' Aquilapollenites''. Other fossils recovered from the formation are: * '' Pucapristis branisi''Leonardi, 1994, p.30 * '' Gasteroclupea branisai'' * '' Coelodus toncoensis'' * '' Dolichochampsa minima'' ;Ichnofossils * '' Hadrosaurichnus australis'' * '' Salfitichnus mentoor''Leonardi, 1994, p.79 * '' Taponichnus donottoi'' * '' Telosichnus saltensis'' * '' Yacoraitichnus avis''

References

Bibliography

* * * {{ISBN, 0-520-24209-2 Geologic formations of Argentina Upper Cretaceous Series of South America Cretaceous Argentina Maastrichtian Stage of South America Cretaceous–Paleogene boundary Paleocene Series of South America Paleogene Argentina Danian Stage Sandstone formations Limestone formations Deltaic deposits Ichnofossiliferous formations Formations Fossiliferous stratigraphic units of South America Paleontology in Argentina Geology of Jujuy Province Geology of Salta Province

Fossil content

See also

References

Bibliography